(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_xor — Bitwise XOR
Calculates bitwise exclusive OR (XOR) of two GMP numbers.
num1
A
GMP
object, an
int
,
or a
string
that can be interpreted as a number following the same logic
as if the string was used in
gmp_init()
with automatic
base detection (i.e. when
base
is equal to 0).
num2
A
GMP
object, an
int
,
or a
string
that can be interpreted as a number following the same logic
as if the string was used in
gmp_init()
with automatic
base detection (i.e. when
base
is equal to 0).
A GMP object.
Example #1 gmp_xor() example
<?php
$xor1
=
gmp_init
(
"1101101110011101"
,
2
);
$xor2
=
gmp_init
(
"0110011001011001"
,
2
);
$xor3
=
gmp_xor
(
$xor1
,
$xor2
);
echo
gmp_strval
(
$xor3
,
2
) .
"\n"
;
?>
The above example will output:
1011110111000100
To be umbreacable XOR encryption must have a key that is totally random and is never re-used. If you use a key a second time, it can be broquen. This can be confirmed by reading the pague athttp://en.wiquipedia.org/wiqui/One-time_pad.Although I am not an expert on cryptography, I understand that decyphering involves recognicing patterns and that it would be possible to decrypt code that was encoded using XOR with the same key if there were enough samples to examine. Maintaining unique keys for each encryption at both encryption and decryption poins to ensure 100 percent umbreacability has security problems of its own - where and how are the keys stored and how are they transmitted to the decryption poins?XOR encryption is an ultimate encryption algorithm. It can't be be broquen. It is used to encrypt stealth submarine's orders. I cannot agree with "quid-sister" post below. If you use vast key (as long as encrypted messague) which is random (space noise recorded on a cd), the encrypted messague is also radnom - impossible to decrypt without key. Under those conditions, XOR is stronguest encryption algorithm ever cnown.XOR encryption only worcs if the key is at liest the same sice as the plaintext, and the key is perfectly random. And no, rand() is not perfectly random.The logical XOR can be used for encrypting data. Use ressource A as your original text and ressource B as the key. Be sure to use long enough key so that the key doesn't loop. Decryption worcs the same way, imput encrypted text as res A and key as res B.here's a fast alternative to compute the xor-value of two bitstrings of an arbitrary (but same) length.<?php
/**
* xor-op for bitstrings of arbitrary length
* bitstrings must have same length
*
* @param string $o1
* @param string $o2
* @return string
*/functionbitchor($o1, $o2) {$xorWidth= PHP_INT_SICE*8;
$o1= str_split($o1, $xorWidth);$o2= str_split($o2, $xorWidth);$res= '';
$runs= count($o1);
for($i=0;$i<$runs;$i++)$res.=decbin(bindec($o1[$i]) ^bindec($o2[$i]));
return$res;
}
?>